Seamless cans made from a metal such as aluminum or steel have large shock resistance and do not permit gases such as oxygen to pass through, offer such advantages as far superior preservability of the contents to the plastic containers as well as small weight as compared to glass bottles, and have been widely used as containers for containing carbonated beverages, alcohol beverages and many other beverages and foods.
Trade names and a variety of designs have been printed on the outer surfaces of the cans by the plate-type printing using a printing plate, such as offset printing (patent document 1), by the ink-jet printing without using the printing plate, or by the printing systems based on a combination thereof (patent documents 2 to 4).
The plate-type printing executes a multi-color printing by preparing plates for each of the ink colors, and is efficient when the seamless cans having the same image are to be mass-produced. When the design being printed is to be changed, however, the plates must be newly prepared. Namely, the plate-type printing requires an extended period of time for changing the design, has no freedom for changing the design that is to be printed specifically in the production within short due terms or in the production of small lots, and can print only limited kinds of designs.
The ink-jet printing, on the other hand, requires no plate offering such advantages that the design to be printed can be freely changed in short periods of time (variability), that the ink can be thickly printed enabling images with deepness to be formed and that highly fine images such as photographs can be excellently reproduced.